Hydrothermal treatment device, biomass fuel manufacturing plant, hydrothermal treatment method, and biomass fuel manufacturing method

ABSTRACT

A hydrothermal treatment device ( 3 ) is a hydrothermal treatment device ( 3 ) performing hydrothermal treatment by heating high-water-content biomass, the hydrothermal treatment device ( 3 ) including a treatment container ( 21 ) that stores sludge, a sludge supply unit ( 22 ) that supplies the sludge to inside of the treatment container ( 21 ) such that a space (S) is formed in a vertical upper part of the treatment container ( 21 ), a stirrer ( 23 ) that is provided within the treatment container ( 21 ) and stirs stored matter such that counter flows in an up/down direction occur, and a heat transfer tube ( 24 ) that is disposed in a horizontal direction within the treatment container ( 21 ) and heats the sludge with heat of vapor flowing within the heat transfer tube ( 24 ).

TECHNICAL FIELD

The present invention relates to a hydrothermal treatment device, abiomass fuel manufacturing plant, a hydrothermal treatment method, and abiomass fuel manufacturing method.

BACKGROUND ART

Although use of carbon-neutral biomass fuels has gathered attentionbecause of the international carbon dioxide emission regulation, woodpellet that is a representative example of biomass fuels costs high, andsolutions for manufacturing various biomass fuels are under review,including reduction of costs and so on.

One of such solutions for manufacturing a biomass fuel is a method formanufacturing a biomass fuel from high-water-content biomass such assewage sludge. However, high-water-content biomass is not hypergolic,and there is a problem that it is difficult to utilize the biomass as acombustion fuel without drying treatment thereon as pretreatment. Inorder to use high-water-content biomass as a fuel, a large amount ofenergy is required for drying the biomass because it contains muchmoisture to be dewatered for drying, which therefore requires treatmentof impurities contained in the dewatered moisture and increases thecost. Also, in high-water-content biomass, moisture is constrainedwithin biological cell walls, and a low drying efficiency is therefore aproblem.

As a method for improving the efficiency of drying of biomass, a methodhas been known which supplies vapor having a predetermined temperatureand pressure to biomass and thus performs hydrothermal treatment(hydrolysis treatment) thereon so that cell walls of the biomass aredestroyed to increase the drying efficiency (For example, PLT 1 and PLT2).

CITATION LIST Patent Literature

[PTL 1] the Publication of Japanese Patent No. 6190082

[PTL 2] Japanese Unexamined Patent Application, Publication No.2008-100218

SUMMARY OF INVENTION Technical Problem

However, according to the apparatuses disclosed in PLT 1 and PLT 2, thehydrothermal treatment is performed by bringing vapor andhigh-water-content biomass into direct contact. When vapor andhigh-water-content biomass are brought into direct contact, the vapor iscondensed while the high-water-content biomass is being heated, and thecondensed water (drain) is mixed into treated matter (high-water-contentbiomass having undergone the hydrothermal treatment), which increasesthe moisture contained in the treated matter after the hydrothermaltreatment. In order to manufacture a biomass fuel, moisture is requiredto be separated and removed from the treated matter in a process afterthe hydrothermal treatment, but, due to the increase of the moisture ofthe treated matter after the hydrothermal treatment, there is apossibility that the energy required for the separation and removalincreases.

The apparatuses disclosed in PLT 1 and PLT 2 require to export thetreated matter by reducing the temperature and pressure after thehydrothermal treatment for performing batch processing on thehydrothermal treatment and again import and fill the high-water-contentbiomass and increase the temperature and pressure, which further causesa problem that the energy required for the separation and removalincreases and the productivity cannot be improved because preceding andsubsequent treatment times are required in addition to the hydrothermaltreatment time.

The present invention has been made in view of such circumstances, andit is an object of the present invention to provide a hydrothermaltreatment device, a biomass fuel manufacturing plant, a hydrothermaltreatment method, and a biomass fuel manufacturing method that canreduce the water content of treated matter after hydrothermal treatmentand thus reduce energy required for separating and removing moisturefrom the treated matter after the hydrothermal treatment.

Solution to Problem

In order to solve the problem, the hydrothermal treatment device,biomass fuel manufacturing plant, hydrothermal treatment method andbiomass fuel manufacturing method of the present invention adopt thefollowing solutions.

A hydrothermal treatment device according to one aspect of the presentinvention is a hydrothermal treatment device performing hydrothermaltreatment by heating high-water-content biomass, the hydrothermaltreatment device including a treatment container that stores thehigh-water-content biomass, a first supply unit that supplies thehigh-water-content biomass to inside of the treatment container suchthat a space is formed in a vertical upper part of the treatmentcontainer, a stirrer unit that is provided within the treatmentcontainer and stirs the high-water-content biomass such that flows in apredetermined direction occur, and at least one heat transfer tube thatis disposed within the treatment container so as to cross thepredetermined direction and heats the high-water-content biomass withheat of vapor flowing within the heat transfer tube.

In the above-described configuration, high-water-content biomass isheated by heat-exchanging between vapor flowing within the heat transfertube and the high-water-content biomass stored within the treatmentcontainer so that a hydrolysis reaction is caused and thehigh-water-content biomass is hydrothermally treated. By thehydrothermal treatment, moisture constrained within cell walls of thehigh-water-content biomass is emitted. When the moisture is emitted, theemitted moisture and the high-water-content biomass are mixed, whichimproves the flowability of the high-water-content biomass within thetreatment container. Thus, the stirring in the stirrer unit can bepreferably performed. Therefore, the high-water-content biomass withinthe treatment container can uniformly have a hydrolysis reaction, andhydrothermal treatment can thus be preferably performed.

Further in the above-described configuration, heat exchange between thevapor and the high-water-content biomass is performed through the heattransfer tube. In other words, the hydrothermal treatment of thehigh-water-content biomass is performed by heating thehigh-water-content biomass indirectly through the heat transfer tube,without bringing the high-water-content biomass and the vapor intodirection contact. The moisture required for causing thehigh-water-content biomass to flow is covered by effectively utilizingthe moisture contained in the high-water-content biomass. In thismanner, the amount of moisture such as vapor to be given to thehigh-water-content biomass for the hydrothermal treatment can bereduced. Compared with the method that brings the vapor into directcontact, the water content of the treated matter acquired by performingthe hydrothermal treatment on the high-water-content biomass(hereinafter, simply called “treated matter”) can be reduced. Therefore,when moisture is separated and is removed from the treated matter afterthe hydrothermal treatment, the energy required for the separation andremoval of moisture can be reduced.

By heating the high-water-content biomass indirectly through the heattransfer tube, impurities in the high-water-content biomass are notmixed into the vapor flowing within the heat transfer tube. Thus, thevapor and drained hot water flowing within the heat transfer tube can beused for a drying process in another heat exchanger, and, by increasingthe reduced temperature again and supplying them to the heat transfertube again, the high-water-content biomass can be indirectly heated sothat the energy loss can be reduced.

Because a space is formed in a vertical upper part within the treatmentcontainer, a desired pressurizing space can be formed within thetreatment container. Therefore, hydrothermal treatment can be performedin a stable manner within the treatment container. Because of the spaceformed in the vertical upper part of the treatment container, the mixingof newly charged high-water-content biomass and high-water-contentbiomass stored within the treatment container is efficiently performed.Thus, a hydrolysis reaction is promoted so that the hydrothermaltreatment can be preferably performed.

Because the high-water-content biomass is stirred by the stirrer unitsuch that flows in a predetermined direction occur in thehigh-water-content biomass and the heat transfer tube is disposed so asto cross the flows of the high-water-content biomass in thepredetermined direction, more high-water-content biomass can beefficiently brought into contact with the heat transfer tube and can beheated. Thus, a hydrolysis reaction is promoted so that the hydrothermaltreatment can be preferably performed. Therefore, the hydrothermaltreatment time can be reduced.

In the hydrothermal treatment device according to an aspect of thepresent invention, the stirrer unit may include a blade unit disposed soas to tilt from a horizontal plane, the blade unit may rotate about anaxial direction extending in a vertical up/down direction, the bladeunit may have a radial tip disposed so as to be close to an innerperiphery surface of the treatment container, and the heat transfer tubemay extend in a horizontal direction.

When the blade unit rotates about the axial direction extending in thevertical up/down direction, the high-water-content biomass stored withinthe treatment container is pressed by the blade unit. Because the bladeunit tilts from the horizontal plane, a force moving in the verticalupper or vertical down direction acts on the pressed high-water-contentbiomass which thus moves within the treatment container, and thehigh-water-content biomass is preferably stirred.

In the above-described configuration, the heat transfer tube is disposedso as to extend in the horizontal direction. Therefore, the heattransfer tube can be disposed so as to securely cross a counter flow ofthe high-water-content biomass circulating in the vertical up/downdirection. Thus, more high-water-content biomass can be securely broughtinto contact with the heat transfer tube and be heated. Therefore, thehigh-water-content biomass within the treatment container can uniformlyhave a hydrolysis reaction, and hydrothermal treatment can preferably beperformed thereon.

Because the blade unit has a radial tip disposed so as to be close tothe inner periphery surface of the treatment container, adhesion andhardening of the sludge to the inner periphery surface of the treatmentcontainer can be suppressed.

In the above-described configuration, because the blade unit rotatesabout the axis in the up/down direction, the path area of the blade unitis formed so as to extend in the horizontal direction. On the otherhand, the heat transfer tube extends in the horizontal direction. Thus,it is hard for the path area of the blade unit and the heat transfertube to overlap so that it can be hard for the blade unit and the heattransfer tube to interfere with each other.

In the hydrothermal treatment device according to an aspect of thepresent invention, the stirrer unit may include a plurality of bladeunits that rotate about an axial direction extending in a verticalup/down direction, the plurality of blade units may be disposed at equalintervals along a circumferential direction of the axial direction atpositions separated by a predetermined distance in a radial directionfrom the axial direction about which the blade units rotate, and each ofthe blade units may be disposed so as to tilt at a predetermined angletoward a direction of the rotation from a horizontal plane, the heattransfer tube may extend in a horizontal direction, and the flows in thepredetermined direction may be counter flows including flows in thevertical up direction and the vertical down direction.

When the plurality of blade units disposed so as to tilt at apredetermined angle from the horizontal plane rotates about an axis in avertical up/down direction, flows of the high-water-content biomass thatmove in both of the vertical up and vertical down directions occur. Eachof these flows turns in a substantial U shape near the interface (upperend surface) of the stored high-water-content biomass or the bottomsurface of the treatment container and moves in the direction oppositeto the direction of the movement until then. In this manner, counterflows of high-water-content biomass circulating in the vertical up/downdirection occur within the treatment container so that thehigh-water-content biomass is preferably stirred. The heat transfer tubeis disposed so as to extend in the horizontal direction. Thus, the heattransfer tube can be disposed so as to securely cross the counter flowsof the high-water-content biomass circulating in the vertical up/downdirection. Therefore, more high-water-content biomass can be securelybrought into contact with the heat transfer tube and can be heated. As aresult, because the high-water-content biomass within the treatmentcontainer can uniformly have a hydrolysis reaction, hydrothermaltreatment can preferably be performed thereon.

The hydrothermal treatment device according to an aspect of the presentinvention may further include a second supply unit that supplies wateror vapor to the treatment container such that at least a part of storedmatter within the treatment container maintains a predetermined watercontent.

When the high-water-content biomass is heated because of the contactwith the heat transfer tube, moisture thereof evaporates and the watercontent of the stored matter within the treatment container decreases,there is a possibility that the flowability of the stored matter withinthe treatment container decreases, but, in the above-describedconfiguration, water or vapor is supplied to the treatment containersuch that at least a part of the stored matter storing thehigh-water-content biomass within the treatment container can maintain apredetermined water content. Thus, the decrease of the flowability ofthe stored matter can be suppressed. Therefore, because, at all times,the flowability can be maintained and preferable stirring can beperformed, a uniform hydrolysis reaction is caused so that hydrothermaltreatment can be preferably performed. Because the flowability ismaintained, the stored matter having undergone the hydrothermaltreatment can be ejected easily from the treatment container.

In the hydrothermal treatment device according to an aspect of thepresent invention, the treatment container may include an outer shellhaving a body part forming a side surface and a bottom surface and aceiling part forming a vertical upper surface, and a fixing unit thatfixes at least one of the heat transfer tubes to the body part, theceiling part may be removably fixed to the body part, and the fixingunit may be removably fixed to the body part.

In the above-described configuration, the ceiling part can be opened, orthe fixing unit that fixes the heat transfer tube can be removed fromthe body part of the treatment container. In this manner, by removingthe fixing unit from the body part, the heat transfer tube can beaccessed. Therefore, maintenance and repair, for example, of the insideof the treatment container and the heat transfer tube can be easilyperformed.

The hydrothermal treatment device according to an aspect of the presentinvention may further include a supply chamber that supplies thehigh-water-content biomass to the treatment container, an ejectionchamber from which stored matter stored within the treatment containeris ejected, a first switching means that switches between a state thatthe supply chamber and the treatment container are in communication anda state that the supply chamber and the treatment container areisolated, and a second switching means that switches between a statethat the ejection chamber and the treatment container are incommunication and a state that the ejection chamber and the treatmentcontainer are isolated. In this case, by keeping a temperature and apressure within the treatment container at a predetermined temperatureand pressure, the high-water-content biomass may be supplied from thesupply chamber to the treatment container, and the stored matter may beejected from the treatment container to the ejection chamber.

In the above-described configuration, by keeping a temperature and apressure within the treatment container at a predetermined temperatureand pressure, the supply of the high-water-content biomass from thesupply chamber to the treatment container and the ejection of the storedmatter from the treatment container to the ejection chamber areperformed. With this configuration, so-called continuous treatment ofthe hydrothermal treatment of the high-water-content biomass can beperformed. Thus, the treated matter (acquired by performing thehydrothermal treatment on the high-water-content biomass) can becontinuously exported without reducing the temperature within thetreatment container. This eliminates the necessity for exporting thetreated matter by reducing the temperature and pressure after thehydrothermal treatment, importing and filling the high-water-contentbiomass again, and increasing the temperature and pressure, the energyloss due to the temperature reduction of the treatment container andtreated matter in the hydrothermal treatment device required forpreceding and subsequent treatments other than the hydrothermaltreatment can be suppressed, and the time required for the preceding andsubsequent treatment times other than the hydrothermal treatment timecan be suppressed, improving the productivity.

The hydrothermal treatment device according to an aspect of the presentinvention may further include a control unit that adjusts a speed ofrotation of the stirrer unit during hydrothermal treatment within thetreatment container such that a temperature difference depending onpositions of the high-water-content biomass within the treatmentcontainer is within a predetermined temperature difference range.

In the above-described configuration, by the control unit, the number ofrotations of the stirrer unit can be adjusted such that a temperaturedifference depending on positions of the high-water-content biomasswithin the treatment container is within a predetermined temperaturedifference range. Thus, a hydrolysis reaction can be promoted, and thehydrothermal treatment can be preferably performed. Therefore, thehydrothermal treatment time can be reduced.

A biomass fuel manufacturing plant according to an aspect of the presentinvention is a biomass fuel manufacturing plant including theabove-described hydrothermal treatment device, the plant including adewaterer unit that dewaters the high-water-content biomass havingundergone hydrothermal treatment in the hydrothermal treatment device, afirst separated water channel that guides separated water separated fromthe high-water-content biomass in the dewaterer unit to the treatmentcontainer, a vapor ejection unit that ejects vapor occurring within thetreatment container to outside of the treatment container, and aseparation treatment unit that separates impurities from the vaporejected from the vapor ejection unit.

The vapor occurring within the treatment container contains a volatileconstituent (such as CH4, benzene and HmSn compound) and impuritiescontained in the high-water-content biomass. Therefore, in theseparation treatment unit, treatment for separating the volatileconstituent and impurities is performed on the vapor ejected from thetreatment container.

Because the separated water separated in the dewaterer unit alsocontains a volatile constituent and impurities contained in thehigh-water-content biomass, the treatment for separating the volatileconstituent and impurities is necessary. In the above-describedconfiguration, the separated water separated by the dewaterer unit isguided to the treatment container. Thus, the separated water evaporateswithin the treatment container, and the resulting vapor is ejected fromthe vapor ejection unit and is treated in the separation treatment unit.In this manner, because the separated water and the vapor occurring inthe treatment container are treated by one separation treatment unit,the structure of the biomass fuel manufacturing plant can be simplifiedmore than a configuration having a separation treatment unit for each ofthe separated water and the vapor. Therefore, the required space can besaved, and the cost for installing it can be reduced.

The biomass fuel manufacturing plant according to an aspect of thepresent invention may further include a plurality of branch pipes whichare branched off from the first separated water channel. In this case,the plurality of branch pipes may be in communication with differentpositions in the vertical up/down direction of the treatment container.

In the above-described configuration, because the branch pipes are incommunication with different positions in the vertical up/down directionof the treatment container, the separated water can be utilized forpurging the stored matter stored within the treatment container.

Therefore, for example, when the branch pipes are connected near anupper surface of the stored matter stored within the treatmentcontainer, the separated water can be sprayed to the heat transfer tubedisposed near the upper surface to purge the high-water-content biomass,which can suppress the fixing of the high-water-content biomass to theheat transfer tube disposed near the upper surface.

For example, when the branch pipes are connected in vicinity of anejection port of the treatment container, the separated water is sprayedto the ejection port which may possibly be clogged with the storedmatter to purge the stored matter, which can suppress the blockage ofthe ejection port.

The biomass fuel manufacturing plant according to an aspect of thepresent invention may further include a blow off pipe that externallyejects a predetermined proportion of separated water separated in thedewaterer unit.

It is preferable not to supply and store, for example, sodium (Na),potassium (K), phosphorus (P) and the like, which are impurityconstituents contained in the separated water, to the treatmentcontainer and not to increase the density of the impurity constituents.In the above-described configuration, because the separated water isguided to the treatment container, there is a possibility that, as theoperation of the plant continues, the impurities are stored and thedensity of the impurities increases, but because a predeterminedproportion of separated water is externally ejected by the blow offpipe, the state that the density of impurities increases can besuppressed. Thus, the crystallization of the impurities can besuppressed. Therefore, an increase of the viscosity of the stored matterdue to the crystallization of the impurities within the treatmentcontainer can be suppressed, and the promotion of a hydrolysis reactionby the stirring within the treatment container and the ejection of thetreated matter from the treatment container can be smoothly performed.

The biomass fuel manufacturing plant according to an aspect of thepresent invention may further include a boiler that generates vapor withheat of combustion of a charged fuel supplies the generated vapor to theheat transfer pipe, and a first heat exchanger unit that heat-exchangesbetween the high-water-content biomass having undergone the hydrothermaltreatment in the hydrothermal treatment device and boiler exhaust gasejected from the boiler.

In the above-described configuration, heat exchange is performed betweenboiler exhaust gas from the boiler that generates vapor to be used inthe hydrothermal treatment device and the treated matter havingundergone the hydrothermal treatment so that the treated matter acquiredby performing the hydrothermal treatment on high-water-content biomassis heated with the exhaust gas. In this manner, because the treatedmatter having undergone the hydrothermal treatment can be dried byeffectively utilizing the heat of the boiler exhaust gas, the energyefficiency of the whole biomass fuel manufacturing plant can be improvedcompared with the configuration which does not utilize the heat of theboiler exhaust gas.

The biomass fuel manufacturing plant according to an aspect of thepresent invention may further include a digester to which thehigh-water-content biomass before being supplied to the treatmentcontainer is introduced, a second separated water channel that guidesthe separated water separated from the high-water-content biomass in thedewaterer unit to the digester, an internal combustion engine thatdrives by burning fuel gas for the internal combustion engine containingfuel gas ejected from the digester, and a second heat exchanger unitthat heat-exchanges between the high-water-content biomass havingundergone the hydrothermal treatment in the hydrothermal treatmentdevice and internal combustion engine exhaust gas ejected from theinternal combustion engine.

In the above-described configuration, fuel gas is taken out, in thedigester, from high-water-content biomass before being supplied to thetreatment container, and the internal combustion engine is driven withthe fuel gas for the internal combustion engine containing the takenfuel gas. By heat-exchanging between the exhaust gas from the internalcombustion engine and the treated matter acquired by performinghydrothermal treatment on high-water-content biomass, the treated matteris heated with the internal combustion engine exhaust gas. In thismanner, because the treated matter having undergone the hydrothermaltreatment can be dried by effectively utilizing the heat of the exhaustgas from the internal combustion engine, the energy efficiency of thewhole biomass fuel manufacturing plant can be improved compared with theconfiguration which does not utilize the heat of exhaust gas from theinternal combustion engine.

By guiding the separated water to the digester, the heat required in thedigester is given. In this manner, because potential heat of theseparated water separated from the dewaterer unit is effectivelyutilized, the energy efficiency of the whole biomass fuel manufacturingplant can be improved compared with the configuration which does notutilize the heat of the separated water.

The biomass fuel manufacturing plant according to an aspect of thepresent invention may further include a boiler that generates vapor withheat of combustion of a charged fuel and supplies the generated vapor tothe heat transfer tube, a digester to which the high-water-contentbiomass before being supplied to the treatment container is introduced,a second separated water channel that guides the separated waterseparated from the high-water-content biomass in the dewaterer unit tothe digester, an internal combustion engine that drives by burning fuelgas for the internal combustion engine containing fuel gas ejected fromthe digester, and a third heat exchanger unit that heat-exchangesbetween the high-water-content biomass having undergone the hydrothermaltreatment in the hydrothermal treatment device and boiler exhaust gasejected from the boiler and internal combustion engine exhaust gasejected from the internal combustion engine.

In the above-described configuration, the heat exchange between theboiler exhaust gas, the internal combustion engine exhaust gas and thehigh-water-content biomass having undergone hydrothermal treatment isperformed by one heat exchanger unit. Therefore, the required space canbe saved, and the cost for installing it can be reduced, compared withthe configuration in which a heat exchanger unit that heat-exchangesbetween the boiler exhaust gas and the high-water-content biomass and aheat exchanger unit that heat-exchanges between the internal combustionengine exhaust gas and the high-water-content biomass are separatelyprovided.

The biomass fuel manufacturing plant according to an aspect of thepresent invention may further include a fourth heat exchanger unit thatheat-exchanges between the high-water-content biomass having undergonethe hydrothermal treatment in the hydrothermal treatment device andvapor ejected from the heat transfer tube.

In the above-described configuration, the treated matter can be heatedwith the heat of the vapor ejected from the heat transfer tube. In thismanner, because potential heat of the vapor ejected from the heattransfer tube is effectively utilized, the energy efficiency of thewhole biomass fuel manufacturing plant can be improved compared with theconfiguration which does not utilize the heat of the vapor ejected fromthe heat transfer tube.

The biomass fuel manufacturing plant according to an aspect of thepresent invention may further include a fifth heat exchanger unit thatheat-exchanges between vapor ejected from the heat transfer tube and theseparated water ejected from the dewaterer unit.

In the above-described configuration, the separated water can be heatedwith the heat of the vapor ejected from the heat transfer tube. In thismanner, because potential heat of the vapor ejected from the heattransfer tube is effectively utilized, the energy efficiency of thewhole biomass fuel manufacturing plant can be improved compared with theconfiguration which does not utilize the heat of the vapor ejected fromthe heat transfer tube.

The biomass fuel manufacturing plant according to an aspect of thepresent invention may further include a high-water-content biomass tankthat stores the high-water-content biomass to be supplied to thetreatment container, and a sixth heat exchanger unit that heat-exchangesbetween vapor ejected from the heat transfer tube and thehigh-water-content biomass within the high-water-content biomass tank.

In the above-described configuration, the high-water-content biomass tobe supplied to the treatment container can be heated with the heat ofthe vapor ejected from the heat transfer tube. In this manner, becausepotential heat of the vapor ejected from the heat transfer tube iseffectively utilized, the energy efficiency of the whole biomass fuelmanufacturing plant can be improved compared with the configurationwhich does not utilize the heat of the vapor ejected from the heattransfer tube.

A hydrothermal treatment method according to an aspect of the presentinvention is a hydrothermal treatment method performing hydrothermaltreatment by heating high-water-content biomass, the hydrothermaltreatment method including a supplying step of supplying thehigh-water-content biomass to inside of a treatment container such thata space is formed in a vertical upper part of the treatment container, astirring step of, by a stirrer unit provided within the treatmentcontainer, stirring the high-water-content biomass such that flows in apredetermined direction occur, and a heating step of heating thehigh-water-content biomass with vapor flowing within at least one heattransfer tube disposed within the treatment container so as to cross thepredetermined direction.

A biomass fuel manufacturing method according to an aspect of thepresent invention manufactures a biomass fuel by using the hydrothermaltreatment method.

Advantageous Effects of Invention

The water content of treated matter after hydrothermal treatment can bereduced, and the energy required for separating and removing moisturefrom the treated matter after the hydrothermal treatment can be reduced.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic configuration diagram of a biomass fuelmanufacturing plant according to a first embodiment of the presentinvention.

FIG. 2 is a schematic diagram showing a schematic section of ahydrothermal treatment device in FIG. 1 and an overview of a connectionbetween the hydrothermal treatment device and other devices.

FIG. 3 is a schematic front view showing a stirrer in FIG. 2.

FIG. 4 is a diagram showing flows of stored matter within a treatmentcontainer in FIG. 2.

FIG. 5 is a schematic diagram showing a lateral end face of thetreatment container in FIG. 2.

FIG. 6 is a time chart showing open/closed states of valves, fillingamounts and pressure in a supply chamber, and storage amounts of thetreatment container.

FIG. 7 is a schematic diagram showing a modification of FIG. 2.

FIG. 8 is a schematic configuration diagram of a biomass fuelmanufacturing plant according to a second embodiment of the presentinvention.

FIG. 9 is a schematic configuration diagram showing a modification ofFIG. 8.

DESCRIPTION OF EMBODIMENTS

Embodiments of a hydrothermal treatment device, a biomass fuelmanufacturing plant, a hydrothermal treatment method and a biomass fuelmanufacturing method according to the present invention are describedbelow with reference to drawings.

In the following description, “up” as in “upper” and “up direction” and“down” in similar expressions indicate “up” and “down” in a verticaldirection.

First Embodiment

A first embodiment of the present invention is described below withreference to FIGS. 1 to 5.

A biomass fuel manufacturing plant 1 according to this embodimentincludes, as shown in FIG. 1, a boiler 2 that generates vapor, ahydrothermal treatment device 3 that performs hydrothermal treatment on,for example, sludge (high-water-content biomass) by using heat of thevapor from the boiler 2, a dewaterer (dewaterer unit) 4 that dewatersthe sludge (hereinafter, called “treated matter”) having undergone thehydrothermal treatment in the hydrothermal treatment device 3, a firstdrier (fourth heat exchanger unit) 5 and a second drier (first heatexchanger unit) 6 that dries the treated matter dewatered in thedewaterer 4, and a molding machine 7 that molds the treated matter driedin the first drier 5 and the second drier 6 to a biomass fuel. Thebiomass fuel manufacturing plant 1 further includes a sludge dewaterer 9that dewaters the sludge from a sewage treatment facility 8 before thesludge is introduced to the hydrothermal treatment device 3, and asludge storage tank (high-water-content biomass tank) 17 thattemporarily stores the sludge dewatered in the sludge dewaterer 9. Fromthe separated water separated in the sludge dewaterer 9, impurities anda volatile constituent (such as CH4, benzene and HmSn compound)contained in the separated water are separated and removed in atreatment plant.

In the following description, although an example in which sewage sludgesupplied from the sewage treatment facility 8 is used is described as anexample of a raw material of a biomass fuel, the raw material to betreated in the biomass fuel manufacturing plant 1 is not limited tosewage sludge. High-water-content biomass (wetting fuel) is onlyrequired.

The boiler 2 includes a furnace (not shown) to which fuel and air (notshown) supplied from a fuel supply pipe 10 are supplied and a burner(not shown) that forms flame within the furnace, and feedwater is heatedwith heat of combustion acquired by burning the fuel with the burner togenerate vapor.

A vapor supply pipe 11 is connected to the boiler 2. The vapor generatedin the boiler 2 is supplied to a heat transfer tube 24 in thehydrothermal treatment device 3 through the vapor supply pipe 11. Athermometer 12 that measures a temperature of the vapor flowing withinthe vapor supply pipe 11 is provided, for example, on an exit side ofthe boiler 2 or on an entrance side of the heat transfer tube 24 of thevapor supply pipe 11 (refer to FIG. 2). When the temperature of thevapor measured by the thermometer 12 is lower than a predeterminedvalue, the fuel to be supplied to the burner is increased to increasethe temperature of the vapor.

A boiler exhaust gas pipe 13 is further connected to the boiler 2.Boiler exhaust gas ejected from the boiler 2 is supplied to the seconddrier 6 through the boiler exhaust gas pipe 13. The boiler exhaust gasejected from the boiler 2 has, for example, about 300° C. to 400° C.

The boiler exhaust gas that is a heat source for drying the treatedmatter in the second drier 6 is ejected from the second drier 6. Afterthe boiler exhaust gas ejected from the second drier 6 is deodorized bya deodorizer 14, impurities such as dust are removed therefrom in a dustremover 15, and the resulting gas is then emitted to the air from achimney 16.

The hydrothermal treatment device 3 includes, as shown in FIG. 2, atreatment container 21 within which hydrothermal treatment is performed,a sludge supply unit (first supply unit) 22 that introduces sludge fromthe sewage treatment facility 8 to the treatment container 21, a stirrer(stirrer unit) 23 that is disposed within the treatment container 21 andstirs sludge stored within the treatment container 21, at least one heattransfer tube 24 that is disposed within the treatment container 21 andwithin which vapor flows, and a treated-matter ejecting unit 25 thatejects treated matter from the treatment container 21.

In high-water-content biomass such as sludge, moisture may beconstrained within biological cell walls, and it is difficult for theconstrained moisture to be evaporated, reducing the drying efficiency.In the hydrothermal treatment device 3, because of a hydrolysis reactionusing heat of the vapor generated in the boiler 2, cell walls of thehigh-water-content biomass are destroyed to emit the moistureconstrained within the cells. In other words, sludge is hydrothermallytreated in the hydrothermal treatment device 3. The hydrothermaltreatment is preferably performed on the high-water-content biomass byincreasing the pressure and temperature of the high-water-contentbiomass to acquire a predetermined temperature (150 degrees to 230degrees) under a condition that the pressure is equal to a predeterminedpressure (0.5 Mpa to 3 Mpa).

The treatment container 21 in this embodiment is, for example, asubstantially cylindrical pressure container about a vertical up/downdirection as an axis and has a lower end part that is a bottom surfaceand is bent hemispherically. The treatment container 21 has a body part21 b forming a lower end part that is a side surface and a bottomsurface of an outer shell and a ceiling part 21 a. The ceiling part 21 aof the treatment container 21 is formed to have a planer shape and isfixed removably from the body part 21 b, and a first vapor ejection pipe26 and a third sludge pipe 35, which are described below, are connectedto the ceiling part 21 a. The bent low end part has an ejection port(not shown) from which stored matter within the treatment container 21is ejected to outside and is connected to the treated-matter ejectingunit 25. The treatment container 21 further has the body part 21 bforming the outer shell and a tube support (fixing unit) 21 c that fixesthe heat transfer tube 24 to the body part 21 b (refer to FIG. 5).Although the tube support 21 c is fixed to the body part 21 b, the tubesupport 21 c and the body part 21 b are separately provided so that thetube support 21 c can be removed from the body part 21 b.

Sludge is stored within the treatment container 21. In more detail,while sludge having a water content of about 70% to 90% (80% to 85% morepreferably) is stored in a part from a middle area to a lower area inthe vertical up/down direction of the space within the treatmentcontainer 21, a space S that does not store sludge is formed in an upperarea. Inside of the treatment container 21, pressure (about 0.5 Mpa to 3Mpa) is kept which allows hydrothermal treatment to be preferablyperformed on the sludge. A pressure gauge 27 that measures a pressurewithin the treatment container 21 is provided in the treatment container21, and the measured value is sent to a control unit 18.

The control unit 18 includes, for example, a central processing unit(CPU), a random access memory (RAM), a read only memory (ROM), and acomputer readable storage medium. A series of processes for implementingfunctions is stored in, for example, the storage medium in a programform, and the CPU reads out the program to, for example, the RAM andexecutes processing and arithmetic operations on information toimplement the functions. The program may be pre-installed in the ROM oranother storage medium, may be stored in a computer readable storagemedium and be provided or may be distributed through a wired or wirelesscommunication means, for example. The computer readable storage mediumis a magnetic disk, a magneto-optical disk, a CD-ROM, a DVD-ROM, asemiconductor memory or the like.

The first vapor ejection pipe (vapor ejection unit) 26 that ejects vaporto outside of the treatment container 21 is connected to the ceilingpart 21 a of the treatment container 21. A flow rate adjustment valve 26a that adjusts the flow rate of the vapor flowing within the first vaporejection pipe 26 is provided in the first vapor ejection pipe 26. Thecontrol unit 18 changes the flow rate adjustment valve 26 a to an openstate when the pressure within the treatment container 21 measured bythe pressure gauge 27 is equal to or higher than a threshold value beinga predetermined pressure (such as a predetermined pressure (0.5 Mpa to 3Mpa) at which the hydrothermal treatment is performed), and the excessvapor within the treatment container 21 is ejected to outside so thatthe pressure within the treatment container 21 becomes equal to or lowerthan the predetermined threshold to maintain the pressure state forperforming the hydrothermal treatment.

A condenser 28 is provided in the first vapor ejection pipe 26 on adownstream side from the flow rate adjustment valve 26 a, and vaporejected from the treatment container 21 is condensed in the condenser28. From the condensed water that is condensed, impurities and avolatile constituent (such as CH4, benzene and HmSn compound) containedin the condensed water are separated and are removed in a treatmentfacility (separation treatment unit) 29. The treatment facility 29 towhich the condensed water is introduced may be the same facility as thetreatment facility to which the separated water that is separated isintroduced from the sludge dewaterer 9 or may be other facility.

The sludge supply unit 22 includes a supply chamber 31 that temporarilystores sludge, a feeder 32 that adjusts the amount of sludge to besupplied into the treatment container 21, a first sludge pipe 33 thatsupplies sludge to the supply chamber 31, a second sludge pipe 34 thatsupplies the sludge ejected from the supply chamber 31 to the feeder 32,and a third sludge pipe 35 that introduces the sludge from the feeder 32into the treatment container 21.

Sludge flows within the first sludge pipe 33, and the first sludge pipe33 has a downstream end part connected to the supply chamber 31. A firstsupply side valve 22 a is provided in the first sludge pipe 33. Thefirst supply side valve 22 a is a ball valve, for example, that is avalve having a high seal performance which allows sludge to pass throughat an open state and allows the pressure within the supply chamber 31 toincrease at a closed state.

The supply chamber 31 is a pressure container the internal pressure ofwhich is adjustable, and sludge is supplied thereto from the firstsludge pipe 33. The pressure within the supply chamber 31 is increasedby supply of pressurized gas (not shown) such as compressed air thereto.A leak channel 31 a is connected to the supply chamber 31. A leak valve31 b is provided in the leak channel 31 a, and, when the leak valve 31 bis changed to have an open state, the pressure within the supply chamber31 can be reduced.

The second sludge pipe 34 connects the supply chamber 31 and the feeder32. In other words, sludge ejected from the supply chamber 31 issupplied to the feeder 32 through the second sludge pipe 34. A secondsupply side valve (first switching means) 22 b and a third supply sidevalve (first switching means) 22 c in order from the upstream side areprovided in the second sludge pipe 34. Each of the second supply sidevalve 22 b and the third supply side valve 22 c is, for example, a ballvalve that is a valve having a high seal performance which allows sludgeto pass through at an open state and allows the pressure within thesupply chamber 31 to increase at a closed state. In other words, thesecond supply side valve 22 b and the third supply side valve 22 c canswitch between a state that the supply chamber 31 and the treatmentcontainer 21 are in communication and a state that the supply chamber 31and the treatment container 21 are isolated from each other. The thirdsupply side valve 22 c is provided as an auxiliary valve for the secondsupply side valve 22 b and prevents stop of the whole hydrothermaltreatment device 3 due to a failure of the second supply side valve 22b.

The feeder 32 is configured to be able to adjust the amount of sludge tobe supplied to the treatment container 21. The third sludge pipe 35 isconnected to the feeder 32, and the feeder 32 introduces a predeterminedamount of sludge to the treatment container 21 through the third sludgepipe 35.

Operations of the first supply side valve 22 a, leak valve 31 b, secondsupply side valve 22 b, third supply side valve 22 c and feeder 32 arecontrolled by the control unit 18.

The stirrer 23 includes a rotation axis 41 that extends about an axisdirection extending in the vertical up/down direction, a plurality ofstick units 42 that extend in the horizontal direction from the rotationaxis 41 and a blade unit 43 provided at a tip part of each of the stickunits 42.

The rotation axis 41 extends so as to be matched with the center axis ofthe cylindrical treatment container 21 across the substantially all areain the up/down direction of the treatment container 21 and rotates incounterclockwise direction viewed from the top. An upper part of therotation axis 41 extends through the ceiling part 21 a of the treatmentcontainer 21. In other words, the rotation axis 41 has an upper end partdisposed outside of the treatment container 21. The upper end part ofthe rotation axis 41 is connected to a rotation driving device (notshown) such as a motor, and the rotation axis 41 rotates at apredetermined number of rotations with driving force from the rotationdriving device such as a motor. The operation of the rotation drivingdevice is performed by the control unit 18. The rotation driving devicemay be configured to be able to measure a rotational load (such as acurrent value) against the number of rotations. The part where therotation axis 41 extends through the ceiling part 21 a has a sealstructure 44 that is a structure preventing gas within the treatmentcontainer 21 from leaking from the through part. The seal structure 44may be, for example, a lip seal of elastic resin or may be a structurehaving a labyrinth seal in which pressured gas is introduced from anexternal opening of the labyrinth seal.

The stick units 42 are stick-shaped members each extending apredetermined distance in the horizontal direction from the rotationaxis 41. In this embodiment, the stick units 42 are fixed at a pluralityof positions (three positions, for example, in this embodiment) in thedirection of extension of the rotation axis 41, and, as shown in FIG. 3,at the fixed positions of the stick units 42, two stick units 42 havingan equal length are provided at intervals of 180 degrees along thecircumferential direction of the outer circumferential surface of therotation axis 41 by a predetermined radial distance (such as 30% to 80%of the distance from the rotation axis 41 to the inner periphery surfaceof the treatment container 21). In other words, in this embodiment,because two stick units 42 are provided at each of the three positionsin the direction of extension of the rotation axis 41, a total of sixstick units 42 are formed.

As shown in FIGS. 2 and 3, a plate-shaped blade unit 43 is provided at aradial tip of each of the stick units 42. The plate-shaped blade unit 43is provided such that a surface part thereof tilts from a horizontalplane at a predetermined angle (such as 5 degrees to 40 degrees) withrespect to the direction of rotation. In more detail, according to thisembodiment, a front part in the direction of movement of the blade unit43 (that is, the direction of rotation of the rotation axis 41) tilts tobe positioned upper than a rear part and form the predetermined anglefrom the horizontal plane. Each of the blade units 43 has a radial tip(that is, end part on the opposite side of the end to which the stickunit 42 is fixed) which is disposed closely to but not in contact withthe inner periphery surface of the treatment container 21.

Here, flows of the stored matter within the treatment container 21 aredescribed with reference to FIG. 4. When the blade units 43 rotate aboutthe rotation axis 41, the blade units 43 press the stored matter storedwithin the treatment container 21. In more detail, stored matter in aradially outer area from the rotation axis 41 within the treatmentcontainer 21 of the stored matter stored within the treatment container21 is pressed. Because the front part in the direction of movement ofthe blade units 43 tilts to be positioned upper than the rear part, aforce that moves downward acts on the pressed stored matter. Therefore,as shown in FIG. 4, the stored matter pressed by the blade units 43moves downward (refer to the arrows in FIG. 3) along the inner peripherysurface of the treatment container 21. The stored matter having moveddownward turns in a substantial U shape near the bottom surface of thetreatment container 21 and moves upward along the center axis. In thismanner, counter flows of the stored matter circulating in the up/downdirection occur in the treatment container 21. The counter flows areformed so as to be substantially symmetrical with respect to therotation axis 41 in all area within the treatment container 21. Becauseof the counter flows, the stored matter stored within the treatmentcontainer 21 is efficiently stirred.

The flows of the stored matter caused within the treatment container 21may be different flows. For example, counter flows may be caused whichmove downward along the rotation axis 41 and move upward along the innerperiphery surface of the treatment container 21. In order to cause suchcounter flows, the blade units 43 may be tilted such that the frontparts in the direction of movement of the rotation are positioned lowerthan the rear parts, or the direction of rotation of the rotation axis41 may be reversed.

As shown in FIG. 3, an elastic buffer 45 (such as a brush) is providedat the tip of each of the blade units 43. The blade units 43 have theradial tips disposed closely to but not in contact with the innerperiphery surface of the treatment container 21 so that sludge issuppressed from being attached to and hardened on the inner peripherysurface of the treatment container 21. The elastic buffer 45 is disposedclosely to or in contact with the inner periphery surface of thetreatment container 21. Providing the elastic buffer 45 can furtherprevent sludge from being adhered to and hardened on the inner peripherysurface of the treatment container 21.

The numbers of the stick units 42 and the blade units 43 are not limitedto the numbers in the description above. Having described above theconfiguration in which the stick units 42 are fixed at three positionsin the direction of extension of the rotation axis 41, the stick units42 may be fixed at a single fixing position or a plurality of fixingpositions other than the three positions. FIG. 1 shows an example inwhich the stick units 42 and the blade units 43 are fixed at fivepositions.

The number of stick units 42 to be fixed to the fixing positions is notlimited to the number described above. Although the example in which twostick units 42 are provided at intervals of 180 degrees is described,the number of stick units 42 to be provided may be, for example, asingle stick unit 42 or may be three or more stick units 42. When aplurality of stick units 42 are provided, the stick units 42 aredesirably provided at equal intervals along the circumferentialdirection of the outer circumferential surface of the rotation axis 41in order to improve the stirring ability. In other words, for example,when four stick units 42 are provided at one fixing position, the stickunits 42 are desirably disposed in the shape of a cross viewed from thetop.

The heat transfer tube 24 is connected to the vapor supply pipe 11, andvapor generated in the boiler 2 is supplied to the heat transfer tube 24through the vapor supply pipe 11. As shown in FIG. 5, at least one ofthe heat transfer tubes 24 is fixed to the tube support 21 c and isremovably fixed to the body part 21 b of the treatment container 21through the tube support 21 c. When the heat transfer tube 24 has, forexample, a spiral coil shape to increase the heating area, the heattransfer tube 24 may be provided near the bottom surface within thetreatment container 21 because it is difficult to removably fix the heattransfer tube 24 to the body part 21 b of the treatment container 21through the tube support 21 c.

In this embodiment, as shown in FIG. 2, the heat transfer tube 24includes a plurality of (in this embodiment, four as an example)horizontal heat transfer tubes 51 extending in the horizontal directionand vertical heat transfer tubes 52 extending in the vertical directionand serially connecting the plurality of horizontal heat transfer tubes51 and is configured to be able to supply vapor as one continuous pipe.

The plurality of horizontal heat transfer tubes 51 may have a heattransfer tube header that connects the plurality of horizontal heattransfer tubes 51 in parallel and can supply and gather vapor, and anadjustment valve (not shown) may be provided between the plurality ofhorizontal heat transfer tubes 51 and the heat transfer tube header (notshown) so as to enable adjustment of the vapor supply balance among theplurality of horizontal heat transfer tubes 51.

Because counter flows of the stored matter circulating in the up/downdirection occur within the treatment container 21 as described above,the horizontal heat transfer tubes 51 are disposed so as to cross theflows.

The plurality of heat transfer tubes 51 are disposed side by side atpredetermined intervals in the up/down direction to shape a layerstructure. In more details, the plurality of horizontal heat transfertubes 51 are disposed such that the horizontal heat transfer tube 51 andthe blade unit 43 of the stirrer 23 are provided alternately in theup/down direction.

As shown in FIG. 5, each of the plurality of horizontal heat transfertubes 51 has a shape extending from the tube support 21 c to theopposite side across the rotation axis 41 and turning a plurality ofnumber of times. In other words, the horizontal heat transfer tube 51has a W-shape viewed from the top. The horizontal heat transfer tubes 51are disposed at positions not interfering with the stirrer 23 where thehorizontal heat transfer tubes 51 and the stirrer 23 are not physicallybrought into contact with each other even when the stirrer 23 rotatesabout the rotation axis 41.

Because the horizontal heat transfer tube 51 at the bottom of theplurality of horizontal heat transfer tubes 51 is near the bottomsurface of the treatment container 21, is therefore not provided betweenthe blade units 43 and does not easily interfere with the stirrer 23,the horizontal heat transfer tube 51 may have a spiral coil shape. Thus,the heating area is increased, and the efficiency of heat transfer ofthe heat transfer tube 24 can be improved.

Each of the vertical heat transfer tubes 52 connects the adjacenthorizontal heat transfer tubes 51. The vertical heat transfer tube 52may connect to the horizontal heat transfer tube 51 fixed to the tubesupport 21 c outside the treatment container 21. The vertical heattransfer tubes 52 may be disposed so as not to interfere with thestirrer 23 in a gap formed between the tips of the blade units 43 andthe inner periphery surface of the treatment container 21.

As shown in FIGS. 1 and 2, the heat transfer tube 24 has a downstreamend connected to a second vapor ejection pipe 53. The second vaporejection pipe 53 is connected to a first heat exchanger 5 a disposedwithin the first drier 5 and guides the vapor and partially drained hotwater ejected from the heat transfer tube 24 to the first drier 5. Thefirst heat exchanger 5 a provided in the first drier 5 heat-exchangesbetween the vapor and drained hot water ejected from the heat transfertube 24 and the treated matter exported from the treatment container 21,heats the treated matter and cools the vapor and the drained hot water.In this case, a large part of the cooled vapor is condensed, and the hotwater having a reduced temperature is mixed with the condensed water.The condensed water that is condensed is supplied to the boiler 2 asfeedwater through a feedwater supply pipe 54 connecting the first drier5 and the boiler 2. The indirect heat exchange performed both in thetreatment container 21 and the first drier 5 prevents mixing ofimpurities and a volatile constituent (CH4, benzene and HmSn compound)to the feedwater. A flowmeter 55 (refer to FIG. 2) that measures theflow rate of the feedwater (condensed water) flowing within thefeedwater supply pipe 54 is provided in the feedwater supply pipe 54. Apipe 57 connected to a feedwater tank 56 merges with an intermediateposition of the feedwater supply pipe 54. When the flow rate measured bythe flowmeter 55 is less than a predetermined rate, feedwater from thefeedwater tank 56 is added.

The treated-matter ejecting unit 25 includes an ejection chamber 61 thattemporarily stores the treated matter, a treated-matter tank 62 thatstores the treated matter to be supplied to the dewaterer 4, a firsttreated-matter pipe 63 that supplies the treated matter ejected from thetreatment container 21 to the ejection chamber 61, a secondtreated-matter pipe 64 that supplies the treated matter ejected from theejection chamber 61 to the treated-matter tank 62, and a thirdtreated-matter pipe 65 that introduces the treated matter from thetreated-matter tank 62 to the dewaterer 4.

The treated matter flows within the first treated-matter pipe 63, andthe first treated-matter pipe 63 has an upstream end connected to theejection port of the treatment container 21 and a downstream endconnected to the ejection chamber 61. A first ejection side valve(second switching means) 25 a and a second ejection side valve (secondswitching means) 25 b in order from the upstream side are provided inthe first treated-matter pipe 63. Each of the first ejection side valve25 a and the second ejection side valve 25 b is, for example, a ballvalve that is a valve having a high seal performance which allows sludgeto pass through at an open state and allows the pressure within theejection chamber 61 to increase at a closed state. In other words, thefirst ejection side valve 25 a and the second ejection side valve 25 bcan switch between a state that the ejection chamber 61 and thetreatment container 21 are in communication and a state that the supplychamber 31 and the treatment container 21 are isolated from each other.The second ejection side valve 25 b is provided as an auxiliary valvefor the first ejection side valve 25 a and prevents stop of the wholehydrothermal treatment device 3 due to a failure of the first ejectionside valve 25 a.

The ejection chamber 61 is a pressure container the internal pressure ofwhich is adjustable, and the treated matter is supplied thereto from thetreatment container 21 through the first treated-matter pipe 63. A leakchannel 61 a is connected to the ejection chamber 61. A leak valve 61 bis provided in the leak channel 61 a, and, when the leak valve 61 b ischanged to have an open state, the pressure within the ejection chamber61 can be reduced.

The second treated-matter pipe 64 connects the ejection chamber 61 andthe treated-matter tank 62. A third ejection side valve 25 c is providedin the second treated-matter pipe 64. The third ejection side valve 25 cis, for example, a ball valve that is a valve having a high sealperformance which allows sludge to pass through at an open state andallows the pressure within the supply chamber 31 to increase at a closedstate.

The third treated-matter pipe 65 connects the treated-matter tank 62 andthe dewaterer 4.

The dewaterer 4 dewaters the sludge (that is, the treated matter)resulting from destruction of the cell walls therein with a hydrolysisreaction in the hydrothermal treatment device 3 by separating the sludgeinto a solid content and a liquid content (separated water). Asdescribed above, because, although moisture is constrained within thebiological cell walls in high-water-content biomass such as sludge, thecell walls are destroyed with a hydrolysis reaction in the hydrothermaltreatment and the moisture constrained within the cell is emitted,efficient dewatering treatment can be performed by the dewaterer 4. Inthe dewaterer 4, the treated matter is dewatered to acquire a watercontent of about 50% or lower, for example. The dewaterer 4 dewaters thetreated matter by, for example, pressing the treated matter by using apressing machine (not shown). The dewaterer 4 may dewater the treatedmatter by other methods. For example, a centrifuge may be used todewater the treated matter.

The operations of the first ejection side valve 25 a, second ejectionside valve 25 b, leak valve 61 b, third ejection side valve 25 c anddewaterer 4 are performed by the control unit 18.

As shown in FIG. 2, the separated water separated in the dewaterer 4 isejected to a separated water pipe (second supply unit, first separatedwater channel) 71, and a large part of the separated water is suppliedto the treatment container 21 through a separated water tank 73, and apart thereof is ejected from a blow off pipe 72, which is describedbelow. At an intermediate position, the separated water pipe 71 has aplurality of branch pipes such as two of a first branch pipe 71 a and asecond branch pipe 71 b in this embodiment, and the pipes are connectedto different positions in the up/down direction of the treatmentcontainer 21 so that spraying therefrom is performed into the treatmentcontainer 21.

The first branch pipe 71 a is connected to a part near an upper surfaceof the stored matter stored within the treatment container 21 (a properposition at 0% to 50% of the height distance from the upper surface tothe lower end part of the treatment container 21 such as a part near thehorizontal heat transfer tube 51 at the top to which sludge introducedinto the treatment container 21 is easily adhered). Through thisconnection, the separated water is sprayed to the horizontal heattransfer tube 51 at the top, and the sludge is purged, which cansuppress the fixing of the sludge. A first flow rate adjustment valve 71c that adjusts the flow rate of the separated water flowing within thefirst branch pipe 71 a is provided in the first branch pipe 71 a.

The second branch pipe 71 b is connected to, for example, a part nearthe ejection port of the treatment container 21. Through thisconnection, the separated water is sprayed to the ejection port whichmay possibly be clogged with the stored matter, and the stored mattersettled and piled in the lower end part is purged, which can suppressthe blockage of the ejection port. A second flow rate adjustment valve71 d that adjusts the flow rate of the separated water flowing withinthe second branch pipe 71 b is provided in the second branch pipe 71 b.

In order to supply the separated water for the purpose of cleaning to apart other than the horizontal heat transfer tube 51 at the top and theejection port, the separated water pipe 71 may have two or more branchesas indicated by the broken line in FIG. 2.

The blow off pipe 72 branches off from the separated water pipe 71 onthe upstream side from the branch positions of the first branch pipe 71a and the second branch pipe 71 b. The blow off pipe 72 has, forexample, a pipe diameter designed such that separated water of apredetermined proportion of 1% to 10% (more preferably 1% to 5%) of theseparated water ejected from the dewaterer 4 flows at all times in theblow off pipe 72. In other words, the remaining separated water thatdoes not branch off to the blow off pipe 72 is supplied to the treatmentcontainer 21.

A flow rate adjustment valve 72 a that adjusts the flow rate of theseparated water flowing within the blow off pipe 72 is provided in theblow off pipe 72. The flow rate adjustment valve 72 a has a degree ofopening to be adjusted in accordance with the density of impurityconstituents contained in the separated water, such as sodium (Na),potassium (K) and phosphorus (P) in plant cells resulting fromdestruction of vegetable fiber (plant cell walls and cell membranes)with a hydrolysis reaction of the sludge and thus adjusts the flow rateof the separated water flowing within the blow off pipe 72. This cansuppress storage of the impurity constituents contained in the separatedwater supplied to the treatment container 21 and crystallization of thestored impurity constituents as a result of an increased density of theimpurity constituents. Therefore, an increase of the viscosity of thestored matter due to the crystallization of the impurity constituentswithin the treatment container 21 can be suppressed, and the promotionof a hydrolysis reaction by the stirring within the treatment container21 and the ejection of the treated matter from the bottom part of thetreatment container 21 can be smoothly performed.

The treated matter resulting from the dewatering of the separated waterin the dewaterer 4 is supplied to the first drier 5 through a fourthtreated-matter pipe 76. The first drier 5 dries the treated matterdewatered in the dewaterer 4 with the first heat exchanger 5 a providedwithin the first drier 5 by using heat of the vapor ejected from thetreatment container 21.

The treated matter dried in the first drier 5 is supplied to the seconddrier 6 through a fifth treated-matter pipe 77. The second drier 6 driesthe treated matter dried in the first drier 5 with the second heatexchanger 6 a provided within the second drier 6 by using heat of theexhaust gas from the boiler 2 such that, for example, the water contentis in a range of 10% to 20% or lower.

The treated matter dried in the second drier 6 is supplied to themolding machine 7 through a sixth treated-matter pipe 78. The moldingmachine 7 molds the treated matter dried in the second drier 6 to abiomass fuel. The biomass fuel molded in the molding machine 7 issupplied to a supply destination. A part of the molded biomass fuel maybe supplied to the boiler 2, as indicated by the broken line in FIG. 1,and may be a part of the fuel for the boiler 2.

Next, operations of the hydrothermal treatment device 3 according tothis embodiment are described with reference to a timing chart in FIG.6. FIG. 6 has a horizontal axis indicating change of time. FIG. 6 has avertical axis (a) indicating open/closed states of the first supply sidevalve 22 a, a vertical axis (b) indicating open/closed states of thesecond supply side valve 22 b and the third supply side valve 22 c. FIG.6 further has a vertical axis (c) indicating filling amounts of sludgein the supply chamber 31, a vertical axis (d) indicating pressure withinthe supply chamber 31, and a vertical axis (e) indicating an amount ofsludge (amount of stored matter) within the treatment container 21. FIG.6 further has a vertical axis (f) indicating open/closed states of thefirst ejection side valve 25 a and the second ejection side valve 25 b,and a vertical axis (g) indicating open/closed states of the thirdejection side valve 25 c.

Initially at T1, the supply chamber 31 and the treatment container 21are separated (isolated) from each other. At T1, the first supply sidevalve 22 a is changed to have an open state (refer to (a)). Because,when the first supply side valve 22 a has an open state at T1, sludge issupplied into the supply chamber 31, the filling amount in the supplychamber 31 increases from T1 to T2 (refer to (c)). At T2 when sufficientsludge is filled into the supply chamber 31, the first supply side valve22 a is changed to have a closed state (refer to (a)). After the insideof the supply chamber 31 is tightly closed, the pressure within thesupply chamber 31 is increased from T2 to T3 (refer to (d)). Thepressure within the supply chamber 31 is increased by supplyingpressurized gas such as compressed air. Upon timing of T3 when thepressure within the supply chamber 31 becomes equal to or higher thanthe pressure within the treatment container 21, the pressure increasingis stopped, and the second supply side valve 22 b and the third supplyside valve 22 c are changed to have an open state (refer to (b)).

When the second supply side valve 22 b and the third supply side valve22 c are changed to have an open state at T3, the supply chamber 31 andthe treatment container 21 become in communication, and, because thesludge within the supply chamber 31 moves to the treatment container 21,the filling amount in the supply chamber 31 decreases, and the amount ofsludge in the treatment container 21 increases, from T3 to T4 (refer to(c) and (e)). At that time, because the tightness of the supply chamber31 is released, the pressure of the supply chamber 31 decreases to apredetermined value (refer to (d)).

At T4, the second supply side valve 22 b and the third supply side valve22 c are changed to have a closed state, and the supply chamber 31 andthe treatment container 21 are separated from each other. From T4 to T5,the treatment container 21 has a tightly closed state, and predeterminedtemperature and pressure states are maintained within the treatmentcontainer 21. At that time, in order for the supply chamber 31 to beable to receive the next sludge, the leak valve 31 b provided in theleak channel 31 a is changed to have an open state, and the pressurewithin the supply chamber 31 is reduced to a pressure equal to theatmospheric pressure (refer to (d)).

From T1 to T5, the ejection chamber 61 and the treatment container 21are separated from each other. Upon timing of T5, the first ejectionside valve 25 a and the second ejection side valve 25 b are changed tohave an open state (refer to (f)).

When the first ejection side valve 25 a and the second ejection sidevalve 25 b are changed to have an open state at T5, the ejection chamber61 and the treatment container 21 become in communication, and, becausethe treated matter at the bottom part within the treatment container 21moves to the ejection chamber 61, the amount of stored matter within thetreatment container 21 decreases from T5 to T6 (refer to (e)). Upontiming of T6 when a predetermined amount of the treated matter isejected from the treatment container 21, the first ejection side valve25 a and the second ejection side valve 25 b are changed to have aclosed state (refer to (f)). The ejection chamber 61 and the treatmentcontainer 21 are separated from each other. Next, the third ejectionside valve 25 c is changed to have an open state at T7, and the treatedmatter is ejected from the ejection chamber 61 (refer to (g)). Upontiming of T8 when the ejection of the treated matter ends, the thirdejection side valve 25 c is changed to have a closed state.

Upon timing of T7, the first supply side valve 22 a is again changed tohave an open state, and preparation for supply of sludge to thetreatment container 21 is started again (refer to (a)). After that, theoperations from T1 to T8 are repeated. The hydrothermal treatment device3 according to this embodiment operates in this manner.

In the hydrothermal treatment device 3, as described above, becauseswitching can be performed between a state that each of the supplychamber 31 and the ejection chamber 61 is in communication with thetreatment container 21 and a state that each of them is separated fromthe treatment container 21, it can be said that the supply of sludge andthe ejection of the treated matter can be continuously performed bymaintaining the temperature and pressure within the treatment container21 at a predetermined temperature and pressure.

Preferably, a predetermined time required up to determination ofcompletion of the hydrothermal treatment on the ejected treated matterunder hydrolysis conditions (the temperature and pressure within thetreatment container 21) and against the amount of supply of new sludgeand the amount of ejection of the treated matter is checked by, forexample, an experiment in advance, and the timing of the supply ofsludge and the timing of the ejection of the treated matter are managedbased on the checked predetermined time.

According to this embodiment, the case is described where the amount ofsludge to be introduced by one operation is set to, for example, 20% ofthe stored matter within the treatment container 21. In other words,when the amount of stored matter within the treatment container 21 is V,the amount of sludge to be introduced by one operation is 0.2V. Thecycle time T that is a time from a time when sludge is introduced to thetreatment container 21 to a time when the next sludge is introduced (thetime from T3 to T9 in FIG. 6) is set to five minutes, for example. Thus,the time required for replacing all of the stored matter within thetreatment container 21 is derived from the following expression (1) andis equal to 25 minutes. In other words, the time for performing thehydrothermal treatment on the sludge introduced into the treatmentcontainer 21 and ejecting the result as the treated matter from thetreatment container 21 to outside is equal to 25 minutes, and a propertime can be secured as a general hydrolysis reaction time.(V/0.2V)×T  (1)

The sludge supply timing and the treated matter ejection timing may bemanaged based on changes of the rotational load against the number ofrotations provided in the rotation driving device for the stirrer 23.Because the viscosity of the stored matter decreases as the hydrothermaltreatment advances, the sludge supply timing and the treated matterejection timing may be managed by monitoring a decrease from apredetermined value of the rotational load (current) against the numberof rotations of the rotation driving device for the stirrer 23.

The measurement of and the operation relating to the number of rotationsof the rotation driving device for the stirrer 23 and the rotationalload (such as a current value) may be performed by a number-of-rotationscontrol unit provided within the control unit 18.

According to this embodiment, as described above, the state that each ofthe supply chamber 31 and the ejection chamber 61 is in communicationwith the treatment container 21 and the state that each of the supplychamber 31 and the ejection chamber 61 is separated from the treatmentcontainer 21 are provided for performing the hydrothermal treatment sothat the supply of sludge and the ejection of the treated matter arecontinuously performed by keeping the temperature and pressure withinthe treatment container 21 at a predetermined temperature and pressure.In other words, according to this embodiment, the hydrothermal treatmentperformed in the hydrothermal treatment device 3 is so-called continuoustreatment. Because the hydrothermal treatment is continuous treatment inthis manner and the ejection of the treated matter can thus be performedwithout reducing the temperature within the treatment container 21, theenergy loss due to the temperature reduction of the treatment container21 and the treated matter in the hydrothermal treatment device 3 can besuppressed.

Although the operations of the hydrothermal treatment device 3 aredescribed above with reference to the example in which the second supplyside valve 22 b and the third supply side valve 22 c perform the sameoperation, the second supply side valve 22 b and the third supply sidevalve 22 c may not perform the same operation. Because the third supplyside valve 22 c is provided as an auxiliary valve for the second supplyside valve 22 b, the open/closed state of the channel may be switchedonly with the second supply side valve 22 b by causing the third supplyside valve 22 c to basically maintain its open state. When anabnormality occurs in the second supply side valve 22 b, the thirdsupply side valve 22 c may be operated to switch the open/closed stateof the channel. The same is true for the first ejection side valve 25 aand the second ejection side valve 25 b, and the first ejection sidevalve 25 a and the second ejection side valve 25 b may not perform thesame operation as described above.

Next, operations of the whole biomass manufacturing plant are described.

First, a method for manufacturing a biomass fuel from sludge by usingthe biomass manufacturing plant is described.

The sludge supplied from the sewage treatment facility 8 to thetreatment container 21 in the hydrothermal treatment device 3 (supplyingstep) is indirectly heated (heating step) through the heat transfer tube24 with the heat of the vapor from the boiler 2 under a predeterminedpressure within the treatment container 21 so that the hydrothermaltreatment is performed on the sludge and cell walls are destroyed by ahydrolysis reaction. At that time, the stored matter within thetreatment container 21 is stirred and is fragmented by the stirrer 23(stirring step).

When the hydrothermal treatment is performed, the pressure within thetreatment container 21 is caused to be a predetermined pressure (0.5 Mpato 3 Mpa), and the temperature within the treatment container 21 is keptat a predetermined temperature (150° C. to 230° C.), by the control unit18. The distribution of temperature within the treatment container 21 ismeasured by a plurality of thermometers 12 a and 12 b provided in theup/down direction within the treatment container 21. The rotationalspeed of the stirrer 23 is adjusted such that a temperature differencebetween the temperature measured by the thermometer 12 a that measures atemperature of an upper part of the stored matter stored within thetreatment container 21 (near a middle part of the treatment container21) and a temperature measured by the thermometer 12 b that measures atemperature of a lower part (near the bottom of the treatment container21) can be within a predetermined temperature difference range (5° C. to10° C.). The pressure within the treatment container 21 increases withvapor pressure occurring from sludge that is heated. After the pressurereaches a predetermined pressure (0.5 Mpa to 3 Mpa), the degree ofopening of the flow rate adjustment valve 26 a provided in the firstvapor ejection pipe 26 is adjusted to maintain the pressure constant.

The treated matter having undergone the hydrothermal treatment in thehydrothermal treatment device 3 and being ejected from the hydrothermaltreatment device 3 is dewatered in the dewaterer 4, and a liquid content(separated water) is separated from the treated matter. The watercontent of the treated matter dewatered in the dewaterer 4 is about 50%.The treated matter dewatered in the dewaterer 4 is supplied to the firstdrier 5 and is dried, in the first drier 5, with heat of the vapor andpartially drained hot water ejected from the heat transfer tube 24 inthe hydrothermal treatment device 3. The treated matter dried in thefirst drier 5 is next supplied to the second drier 6 and is dried withheat of the boiler exhaust gas from the boiler 2. The water content ofthe treated matter dried in the second drier 6 is in a range from 10% to20% or lower. The treated matter dried in the second drier 6 is suppliedto the molding machine 7 and is molded to a biomass fuel, and, in thismanner, a biomass fuel is manufactured. The biomass fuel molded in themolding machine 7 is supplied to a supply destination. A part of themolded biomass fuel may be supplied to the boiler 2 as indicated by thebroken line in FIG. 1 and may be used as a part of the fuel for theboiler 2.

The separated water separated in the dewaterer 4 is ejected from thedewaterer 4, and a large part thereof (about 90% to 99% of the wholeseparated water) is supplied to the treatment container 21 through theseparated water tank 73, and a part (1% to 10%) thereof is ejected fromthe blow off pipe 72. At that time, in order to secure the flowabilityof the stored matter stored within the treatment container 21, theseparated water is supplied to the treatment container 21 such that thewater content (such as about 80% to 85%) that allows continuousmaintenance of the flowability of the stored matter within the treatmentcontainer 21 can be maintained. In more detail, the amount of theseparated water to be supplied to the treatment container 21 is equal tothe amount of excess vapor ejected from the first vapor ejection pipe 26as a result of the occurrence of vapor from heated sludge so that thewater content of the stored matter within the treatment container 21 canbe maintained to a desired value.

A part of the separated water (1% to 10% of the whole separated water,more preferably, 1% to 5%) separated in the dewaterer 4 flows within theblow off pipe 72 at all times and is blown into the boiler 2 and isburnt. The separated water may undergo treatment that removes impuritiesand the like therefrom in a treatment facility, without supplying to theboiler 2.

The flow of sludge and so on in the biomass fuel manufacturing plant 1according to this embodiment is described above.

Next, a flow of the vapor in the biomass fuel manufacturing plant 1 isdescribed.

The vapor generated in the boiler 2 is supplied to the heat transfertube 24 through the vapor supply pipe 11. The supply of the vapor fromthe boiler 2 to the heat transfer tube 24 is controlled based on themeasured temperature of the thermometer 12 provided in the vapor supplypipe 11 (such as at the exit of the boiler) where the vapor to besupplied is saturated vapor or superheated vapor of, for example, about0.8 Mpa to 10 Mpa and has a supply energy equivalent temperature (20degrees to 50 degrees, set in accordance with the amount of sludge to beintroduced to the treatment container 21 by also using a latent heatcontent of the vapor) as a hydrolysis temperature (maintainedtemperature within the treatment container 21). The flow rate of thefeedwater returning from the heat transfer tube 24 may be adjusted with,for example, a feedwater pump such that the temperature within thetreatment container 21 can be maintained to a predetermined temperature(preferably a temperature that can cause a hydrolysis reaction, such as150 degrees to 230 degrees).

The vapor supplied to the heat transfer tube 24 flows within the heattransfer tube 24 and indirectly heats the stored matter within thetreatment container 21 through the heat transfer tube 24. The vapor andpartially drained hot water ejected from the heat transfer tube 24 areintroduced through the second vapor ejection pipe 53 to the first heatexchanger 5 a disposed within the first drier 5. The vapor and hot waterintroduced to the first heat exchanger 5 a indirectly heat the treatedmatter by performing heat exchange with the treated matter with thefirst heat exchanger 5 a, and the vapor is cooled and is condensed and,after the temperature of the hot water is reduced, the resulting wateris mixed to the condensed water. The condensed water that is condensedis ejected from the first drier 5. Because the indirect heat exchange isperformed both in the treatment container 21 and the first drier 5,impurities and a volatile constituent (CH4, benzene and HmSn compound)are not mixed to the feedwater. The condensed water ejected from thefirst drier 5 is again supplied to the boiler 2 as feedwater through thefeedwater supply pipe 54.

The flow of the vapor and so on in the biomass fuel manufacturing plant1 according to this embodiment is described above.

According to this embodiment, following operating effects are provided.

According to this embodiment, sludge is heated by heat-exchangingbetween vapor flowing within the heat transfer tube 24 and the sludgestored within the treatment container 21 so that a hydrolysis reactionis caused and the sludge is hydrothermally treated. By the hydrothermaltreatment, moisture constrained within cell walls of thehigh-water-content biomass is emitted. When the moisture is emitted, theemitted moisture and the high-water-content biomass are mixed, whichimproves the flowability of the high-water-content biomass within thetreatment container 21. Thus, the stirring in the stirrer unit can bepreferably performed. Therefore, the sludge within the treatmentcontainer 21 can uniformly have a hydrolysis reaction, and thehydrothermal treatment can thus be preferably performed.

According to this embodiment, heat exchange between the vapor and thesludge is performed through the heat transfer tube 24. In other words,the hydrothermal treatment of the sludge is performed by heating thesludge indirectly through the heat transfer tube 24, without bringingthe sludge and the vapor into direction contact. The moisture requiredfor causing the stored matter within the treatment container 21 to flowis covered by effectively utilizing the moisture contained in thesludge. In this manner, the amount of moisture such as vapor to be givento the sludge for the hydrothermal treatment can be reduced. Comparedwith a method that brings the vapor into direct contact, the content ofmoisture of the treated matter after the hydrothermal treatment can bereduced. Therefore, when moisture is separated and is removed from thetreated matter after the hydrothermal treatment, the energy required forseparation and removal of the moisture can be reduced.

By heating the sludge indirectly through the heat transfer tube 24,impurities contained in the sludge are not mixed into the vapor flowingwithin the heat transfer tube 24. Thus, the vapor and drained hot waterflowing within the heat transfer tube 24 can be used for a dryingprocess in another heat exchanger (such as the first drier 5), and thesludge can be indirectly heated by increasing the reduced temperature ofthe vapor and drained hot water again and supplying them to the heattransfer tube 24 again so that the energy loss can be reduced.

Because a space is formed in a vertical upper part within the treatmentcontainer 21, a desired pressurizing space can be formed within thetreatment container 21. Therefore, the hydrothermal treatment can beperformed in a stable manner within the treatment container 21. Becauseof the space S formed in the vertical upper part of the treatmentcontainer 21, the mixing of newly charged sludge and sludge storedwithin the treatment container 21 is efficiently performed. Thus, ahydrolysis reaction is promoted so that the hydrothermal treatment canbe preferably performed.

According to this embodiment, because the blade units 43 tilt from thehorizontal plane, counter flows of the high-water-content biomasscirculating in the up/down direction occur within the treatmentcontainer 21. Further according to this embodiment, the horizontal heattransfer tube 51 in the heat transfer tube 24 is disposed so as toextend in the horizontal direction. Therefore, the heat transfer tube 24is disposed so as to cross the counter flows of the high-water-contentbiomass circulating in the up/down direction. Thus, more stored mattercan be brought into contact with the heat transfer tube 24 and beheated. Therefore, a hydrolysis reaction is promoted, and thehydrothermal treatment can preferably be performed. As a result, thehydrothermal treatment time can be reduced.

According to this embodiment, because the blade units 43 rotate aboutthe axis in the vertical up/down direction, the path area of the bladeunits 43 is formed so as to extend in parallel with the horizontalplane. On the other hand, the horizontal heat transfer tubes 51 extendin the horizontal direction. Thus, the path area of the blade unit 43and the horizontal heat transfer tubes 51 are in parallel, and the patharea of the blade units 43 and the horizontal heat transfer tubes 51 donot overlap so that the interference between the blade units 43 and thehorizontal heat transfer tubes 51 can be prevented. Because the verticalheat transfer tubes 52 are provided between the tips of the blade unit43 and the inner periphery surface of the treatment container 21, theinterference between the blade units 43 and the vertical heat transfertubes 52 can be prevented.

Vapor occurs because of the heating of the sludge by the heat transfertube 24 within the treatment container 21, and, with the vapor pressure,the pressure within the treatment container 21 is maintained to apredetermined pressure, and excess vapor is ejected. As an example, whenhydrothermal treatment is performed under conditions with 220° C. and2.5 Mpa, 15% to 30% of the moisture of the sludge is ejected as vapor.In this manner, the water content of the stored matter may decrease fromthe water content thereof when introduced to the treatment container 21,and the water content of the stored matter may decrease to about 50%.When the water content of the stored matter within the treatmentcontainer 21 decreases, the flowability of the stored matter within thetreatment container 21 decreases, possibly causing problem in stirringthe stored matter or ejecting the treated matter from the treatmentcontainer 21.

According to this embodiment, the separated water is supplied to thetreatment container 21 such that the stored matter within the treatmentcontainer 21 can maintain a predetermined water content. Thus, adecrease of the flowability of the stored matter can be prevented.Therefore, because, at all times, the flowability can be maintained andpreferable stirring can be performed, a uniform hydrolysis reaction canbe caused. Because the flowability is maintained, the stored matter caneasily be ejected from the treatment container 21.

According to this embodiment, the tube support 21 c that fixes theceiling part 21 a and the heat transfer tube 24 can be removed from thebody part 21 b of the treatment container 21. In this manner, byremoving the tube support 21 c from the body part 21 b, the heattransfer tube 24 can be accessed. Because the ceiling part 21 a can beopened, the heat transfer tube 24 can more easily be accessed.Therefore, maintenance and repair, for example, of the inside of thetreatment container 21 and the heat transfer tube 24 can be easilyperformed.

According to this embodiment, by the control unit 18, the number ofrotations of the stirrer 23 can be adjusted such that a temperaturedifference depending on positions of the stored matter within thetreatment container 21 is within a predetermined temperature differencerange (5° C. to 10° C.) Thus, the distribution of temperature of thestored matter within the treatment container 21 is suppressed, and ahydrolysis reaction is promoted so that the hydrothermal treatment canpreferably be performed. Therefore, the hydrothermal treatment time canbe reduced.

The vapor occurring within the treatment container 21 contains avolatile constituent (such as CH4, benzene and HmSn compound) andimpurities contained in the sludge. Therefore, in the separationtreatment unit, treatment for separating the volatile constituent andimpurities is performed on the vapor ejected from the treatmentcontainer 21.

Because the separated water separated in the dewaterer 4 also contains avolatile constituent and impurities contained in the sludge, treatmentfor separating the volatile constituent and impurities is required toperform. According to this embodiment, the separated water separated inthe dewaterer unit is guided to the treatment container 21. Thus, theseparated water evaporates within the treatment container 21, and theresulting vapor is ejected from the vapor ejection unit and is treatedin the separation treatment unit. In this manner, because the separatedwater and the vapor occurring in the treatment container 21 are treatedby one separation treatment unit, the structure of the biomass fuelmanufacturing plant 1 can be simplified more than a configuration havinga separation treatment unit for each of the separated water and thevapor. Therefore, the required space can be saved, and the cost forinstalling it can be reduced.

According to this embodiment, by heat-exchanging between the exhaust gasfrom the boiler 2 that generates vapor to be utilized in thehydrothermal treatment device 3 and the treated matter having undergonethe hydrothermal treatment, the treated matter is heated. In thismanner, because the treated matter having undergone the hydrothermaltreatment can be dried by utilizing the heat of the exhaust gas from theboiler 2, the energy efficiency of the whole biomass fuel manufacturingplant 1 can be improved compared with the configuration which does notutilize the heat of the exhaust gas from the boiler 2.

In a case where the hydrothermal treatment is performed in a batch-wisemanner, because a complicated process is performed including a step offilling sludge into the treatment container 21 in the hydrothermaltreatment device 3 every time, a step of increasing the temperature andpressure of the treatment container 21 in which sludge is filled, a stepof holding the state and performing hydrothermal treatment thereon, astep of reducing the pressure in the treatment container 21, and a stepof ejecting the treated matter, energy and time are required. Inparticular, there is a problem regarding treatment speeds that, while asmall proportion of the time required for one batch is used for the“holding step” in which the hydrothermal treatment is performed, thetime for the other process associated therewith is longer.

According to this embodiment, the hydrothermal treatment performed inthe hydrothermal treatment device 3 is so-called continuous treatment.In other words, the treated matter (sludge in which cell walls aredestroyed by the hydrothermal treatment) can be exported withoutreducing the temperature within the treatment container 21. Thus, theloss of the charged energy due to the temperature reduction of thetreatment container 21 and the treated matter in the hydrothermaltreatment device 3 can be suppressed. Compared with the case where thebatch processing is performed, because the step of increasing thetemperature and pressure and the step of reducing the pressure can beeliminated, the hydrothermal treatment can be efficiently performed.

Due to a hydrolysis reaction of the sludge, vegetable fiber (plant cellwalls and cell membranes) is destroyed, and elements such as sodium(Na), potassium (K) and phosphorus (P) in plant cells are mixed into themoisture. Because the moisture of the sludge becomes vapor by beingheated and is ejected from the treatment container 21 and because theseparated water dewatered from the treated matter is returned to thetreatment container 21, for example, the impurities (Na, K, P) arestored within the treatment container 21, and the density of theimpurities increases. Thus, because the impurities are crystalized,which increases the viscosity of the stored matter, there is apossibility that a problem occurs in stirring the stored matter withinthe treatment container 21 or ejecting the treated matter, for example.Also, there is a possibility that the heat transfer efficiency betweenthe stored matter and the heat transfer tube 24 decreases.

According to this embodiment, the blow off pipe 72 is provided so that1% to 10% (more preferably 1% to 5%) of separated water ejected from thedewaterer 4 is ejected all times. Thus, storage and condensation of theimpurities within the treatment container 21 can be suppressed, and anincrease of the viscosity of the stored matter can be suppressed.

[Modification 1]

A first modification of the first embodiment is described below withreference to FIG. 7.

As shown in FIG. 7, a biomass fuel manufacturing plant 81 according tothis modification is different from the first embodiment in thestructure of a vapor ejection pipe in which vapor ejected from thetreatment container 21 flows. Like numbers refer to like constituents inthe first embodiment and this modification, and detailed descriptionthereof is omitted.

A vapor ejection pipe 82 according to this modification is connected tothe supply chamber 31 and the separated water tank 73 in order from theupstream side. In more detail, the vapor ejection pipe 82 is connectedto the heat exchanger provided within the supply chamber 31 and the heatexchanger provided in the separated water tank 73. The vapor ejectedfrom the treatment container 21 flows within the vapor ejection pipe 82,and heat exchange with the sludge within the supply chamber 31 isperformed in the heat exchanger provided within the supply chamber 31.Through this heat exchange, the sludge can be heated with the heat ofthe vapor, and the vapor can be cooled.

The vapor having heated the sludge in the supply chamber 31 undergoesheat exchange with the separated water in the heat exchanger providedwithin the separated water tank 73. Through this heat exchange, theseparated water can be heated with the heat of the vapor, and the vaporcan further be cooled.

The vapor having heated the separated water is introduced to thecondenser 28. Because the cooling of the vapor is advanced, the coolingability in the condenser 28 can be alleviated.

According to this modification, by utilizing the heat of the vaporejected from the treatment container 21, the sludge to be supplied tothe treatment container 21 can be preheated, and the separated water tobe supplied to the treatment container 21 can be preheated. Therefore,the energy efficiency of the whole biomass fuel manufacturing plant 81can be improved compared with the configuration that does not utilizethe heat of the vapor.

The vapor ejected from the treatment container 21 may be guided toanother device, and the heat of the vapor may be utilized. For example,heat exchange may be performed between the vapor ejected from thetreatment container 21 and the sludge dewatered in the sludge dewaterer9 to preheat the sludge.

[Modification 2]

A second modification of the first embodiment is described below.

A biomass fuel manufacturing plant according to this modification isdifferent from the first embodiment in that a temperature differencemeasuring means that measures a temperature difference between a vaportemperature at the entrance of the heat transfer tube 24 and a vaportemperature at the exit of the heat transfer tube 24 and a rotationalspeed changing means that changes the rotational speed of the rotationaxis 41 of the stirrer 23 based on the temperature difference measuredby the temperature difference measuring means are provided. Like numbersrefer to like constituents in the first embodiment and thismodification, and detailed description thereof is omitted.

The temperature difference measuring means includes, for example, thethermometer 12 on the entrance side that measures the vapor temperatureat the entrance of the heat transfer tube 24, an exit-side thermometer(not shown) that measures the vapor temperature at the exit of the heattransfer tube 24, and a calculating unit that calculates a temperaturedifference based on the temperature measured by the thermometer 12 onthe entrance side and the temperature measured by the exit-sidethermometer.

The rotational speed changing means includes, for example, a determiningunit that, if the temperature difference calculated by the calculatingunit is equal to or lower than a predetermined value, determines thatthe heat exchange in the heat transfer tube 24 is not preferablyperformed and soil is adhered to the heat transfer tube 24, and anumber-of-rotations control unit that increases the number of rotationsof the rotation driving device such as a motor that drives the rotationaxis 41 based on information from the determining unit. The determiningunit and the number-of-rotations control unit may be provided within thecontrol unit 18.

The heat transfer tube 24 may have a decreased heat transfer performancebecause, for example, sludge is burnt and is adhered thereto. Accordingto this modification, because the temperature difference measuring meansis provided, the decrease of the heat transfer performance of the heattransfer tube 24 can be easily grasped. Because the rotational speedchanging means is provided, when the heat transfer performance of theheat transfer tube 24 decreases, the rotational speed of the stirrer 23can be increased to increase the speed of a flow of the stored matter sothat the performance of the heat transfer from the heat transfer tube 24to the stored matter can be recovered.

Instead of the rotational speed changing means, a soot blower thatsprays the separated water separated in the dewaterer 4 to the heattransfer tube 24 may be provided. With this configuration, when the heattransfer performance decreases, the separated water can be sprayed tothe heat transfer tube 24 to clean the surface of the heat transfer tube24 and thus recover the heat transfer performance.

[Modification 3]

A third modification of the first embodiment is described below.

A biomass fuel manufacturing plant according to this modification isdifferent from the first embodiment in that a supplying means thatsupplies additional water or vapor into the treatment container 21 uponstart of the operation of the hydrothermal treatment device 3. Likenumbers refer to like constituents in the first embodiment and thismodification, and detailed description thereof is omitted.

Although the sludge before a hydrolysis reaction has a water content ofabout 80% to 85%, which is apparently high, the sludge is solid matter(sponge-like, containing water) and has a low flowability. In otherwords, because, before a hydrolysis reaction, the moisture of the sludgeis constrained within the cell walls, the sludge has a low flowabilitythough the water content is high. Therefore, there is a possibility thatthe stirring of the stored matter cannot preferably be performed uponstart of the operation of the hydrothermal treatment device 3 that isbefore a hydrolysis reaction.

According to this modification, because additional water or vapor issupplied into the treatment container 21 upon start of the operation ofthe hydrothermal treatment device 3, the flowability of the storedmatter can be improved even before a hydrolysis reaction. When ahydrolysis reaction starts, no additional water or vapor is suppliedbecause the constrained moisture is emitted and the flowability can bemaintained with the moisture of the stored matter itself.

A dedicated channel may be provided for the additional water or vapor tobe supplied, or a liquid content remaining within the treatmentcontainer 21 may be kept upon the last stop, and the kept liquid contentmay be supplied.

Second Embodiment

A second embodiment of the present invention is described below withreference to FIG. 8.

A biomass fuel manufacturing plant 91 according to this embodiment isdifferent from the first embodiment mainly in that a digester 92, adesulfurization device 93, a desiloxane device 94, and a gas engine(internal combustion engine) 95 are provided. Like numbers refer to likeconstituents in the first embodiment and the second embodiment, anddetailed description thereof is omitted.

The digester 92 is provided on the upstream side from the sludgedewaterer 9 and receives sludge supplied from the sewage treatmentfacility 8. The digester 92 performs digestive treatment on the suppliedsludge to generate volatile gas such as methane. The separated waterseparated from the dewaterer 4 is supplied to the digester 92 through aseparated water pipe (second separated water channel) 97, and the heatof the separated water is used as a heat source for the digestivetreatment.

The volatile gas generated in the digester 92 is supplied to thedesulfurization device 93 and is desulfurized. The volatile gas (fuelgas) desulfurized in the desulfurization device 93 is supplied to thedesiloxane device 94, and siloxane is removed therefrom. The volatilegas from which siloxane has been removed is supplied to the gas engine95. Although fuel gas for the internal combustion engine is supplied tothe gas engine 95, the gas engine 95 drives by using and burning thevolatile gas as a part or all of the fuel gas for the internalcombustion engine, and internal combustion engine exhaust gas is ejectedfrom the gas engine 95 in response to the driving. The internalcombustion engine exhaust gas ejected from the gas engine 95 has about150° C. to 400° C., for example.

The internal combustion engine exhaust gas ejected from the gas engine95 flows within a gas engine exhaust gas pipe 96. The gas engine exhaustgas pipe 96 merges with the boiler exhaust gas pipe 13. In other words,the internal combustion engine exhaust gas merges with the boilerexhaust gas pipe 13 through the gas engine exhaust gas pipe 96 and isused as a heat source for drying the treated matter in the second heatexchanger 6 a provided in the second drier 6 (third heat exchangerunit). The internal combustion engine exhaust gas used as the heatsource for drying the treated matter in the second drier 6 is ejectedfrom the second drier 6. After the internal combustion engine exhaustgas ejected from the second drier 6 is deodorized in the deodorizer 14,impurities such as dust are removed therefrom in the dust remover 15,and the resulting gas is then emitted to the air from the chimney 16.

Instead of causing the gas engine exhaust gas pipe 96 to merge with theboiler exhaust gas pipe 13, each of them may be independently connectedto the second drier 6. The boiler exhaust gas pipe 13 may be connectedto the second drier (first heat exchanger unit) 6, the gas engineexhaust gas pipe 96 may be connected to a third drier (second heatexchanger unit) that is different from the second drier 6, the heatexchange with the treated matter may be performed in the third drier,and the treated matter may be dried. The third drier is not shown.

According to this embodiment, following operating effects are provided.

According to this embodiment, volatile gas is taken out, in the digester92, from sludge before being supplied to the treatment container 21, andthe gas engine 95 is driven by using the taken volatile gas as a part orall of the fuel gas for the internal combustion engine. Byheat-exchanging between the internal combustion engine exhaust gas fromthe gas engine 95 and the treated matter having undergone thehydrothermal treatment, the treated matter is heated with the exhaustgas and is dried. In this manner, because the treated matter havingundergone the hydrothermal treatment can be dried by utilizing the heatof the internal combustion engine exhaust gas from the gas engine 95,the energy efficiency of the whole biomass fuel manufacturing plant 91can be improved compared with the configuration which does not utilizethe heat of the exhaust gas from the gas engine 95.

By guiding the separated water that is separated from the dewaterer 4 tothe digester 92, the heat required in the digester 92 is given. In thismanner, because the heat of the separated water separated from thedewaterer 4 is utilized, the energy efficiency of the whole biomass fuelmanufacturing plant 91 can be improved compared with the configurationwhich does not utilize the heat of the separated water.

[Modification]

A modification of the second embodiment is described below withreference to FIG. 9.

As shown in FIG. 9, a biomass fuel manufacturing plant 101 according tothis modification is different from the second embodiment mainly in thatthe vapor and partially drained hot water ejected from the heat transfertube 24 in the treatment container 21 are not supplied to the firstdrier 5 but are guided to the separated water tank 73, that the boilerexhaust gas ejected from the boiler 2 is guided to the first drier 5instead of the second drier 6, and that the internal combustion engineexhaust gas ejected from the gas engine 95 is guided to the second drier6. Like numbers refer to like constituents in the second embodiment andthis modification, and detailed description thereof is omitted.

The vapor and partially drained hot water ejected from the heat transfertube 24 are guided to a separated-water-tank heat exchanger 73 aprovided within the separated water tank 73 through a third vaporejection pipe 102. In the separated-water-tank heat exchanger (fifthheat exchanger unit) 73 a, because the vapor and partially drained hotwater are heat-exchanged with the separated water separated in thedewaterer 4, the separated water is heated, and the vapor and partiallydrained hot water are cooled.

The vapor and partially drained hot water heat-exchanged with theseparated water in the separated-water-tank heat exchanger 73 a areguided to the sludge storage tank 17 through a fourth vapor ejectionpipe 103. In more detail, the vapor and partially drained hot water areguided to a sludge-storage-tank heat exchanger 17 a provided within thesludge storage tank 17. In the sludge-storage-tank heat exchanger 17 a,the vapor and partially drained hot water and the sludge areheat-exchanged. Through this heat exchange, the sludge can be heatedwith the heat of the vapor and partially drained hot water, and thevapor and partially drained hot water can be cooled.

The vapor and partially drained hot water heat-exchanged with theseparated water in the sludge-storage-tank heat exchanger 17 a (sixthheat exchanger unit) are guided to a tank 105 through a fifth vaporejection pipe 104. The vapor and drained hot water guided to the tank105 are supplied to the boiler 2 through the pipe 57.

The boiler exhaust gas ejected from the boiler 2 is guided to the firstheat exchanger 5 a provided within the first drier 5 through a boilerexhaust gas pipe 107. The boiler exhaust gas guided to the first heatexchanger 5 a is heat-exchanged with the treated matter. Through thisheat exchange, the treated matter is heated, and the boiler exhaust gasis cooled. The boiler exhaust gas ejected from the first drier 5 isemitted to the air from the chimney 16 through the deodorizer 14 and thedust remover 15.

The internal combustion engine exhaust gas ejected from the gas engine95 is guided to the second heat exchanger 6 a provided within the seconddrier 6 through an internal combustion engine pipe 108. The internalcombustion engine exhaust gas guided to the second heat exchanger 6 a isheat-exchanged with the treated matter. Through this heat exchange, thetreated matter is heated, and the internal combustion engine exhaust gasis cooled. The boiler exhaust gas ejected from the first drier 5 isemitted to the air from a chimney 109.

According to this modification, by utilizing the heat of the vaporejected from the heat transfer tube 24, the separated water to besupplied to the treatment container 21 can be preheated, and the sludgeto be supplied to the treatment container 21 can be preheated.Therefore, the energy efficiency of the whole biomass fuel manufacturingplant 81 can be improved compared with the configuration that does notutilize the heat of the vapor.

The vapor and partially drained hot water having undergone the heatexchange with the separated water in the separated-water-tank heatexchanger 73 a may be guided to the supply chamber 31 instead of thesludge storage tank 17, and heat exchange may be performed between thevapor and partially drained hot water and the sludge within the supplychamber.

The present invention is not limited to the inventions according to theabove-described embodiments, but modifications can be made withoutdeparting from the spirit and scope of the present invention.

For example, having described the example in which, according to theabove-described embodiment, the separated water separated in thedewaterer 4 is introduced to the treatment container 21 so that thewater content of the stored mater within the treatment container 21 ismaintained, the present invention is not limited thereto. For example,vapor generated in the boiler 2 may be supplied to the treatmentcontainer 21 to maintain the water content of the stored matter. Both ofthe vapor from the boiler 2 and the separated water separated in thedewaterer 4 may be supplied to maintain the water content of the storedmatter.

Although a gas engine is used as the internal combustion engine, anelectric generating system including a small boiler and a small vaporturbine may be used.

REFERENCE SIGNS LIST

-   1 biomass fuel manufacturing plant-   2 boiler-   3 hydrothermal treatment device-   4 dewaterer (dewaterer unit)-   5 first drier (fourth heat exchanger unit)-   5 a first heat exchanger-   6 second drier (first heat exchanger unit, third heat exchanger    unit)-   6 a second heat exchanger-   7 molding machine-   8 sewage treatment facility-   9 sludge dewaterer-   10 fuel supply pipe-   11 vapor supply pipe-   12 thermometer-   13 boiler exhaust gas pipe-   14 deodorizer-   15 dust remover-   16 chimney-   17 sludge storage tank (high-water-content biomass tank)-   17 a sludge-storage-tank heat exchanger (sixth heat exchanger unit)-   18 control unit-   35 treatment container-   21 a ceiling part-   21 b body part-   21 c tube support (fixing unit)-   22 sludge supply unit (first supply unit)-   22 a first supply side valve-   22 b second supply side valve (first switching means)-   22 c third supply side valve (first switching means)-   23 stirrer (stirrer unit)-   24 heat transfer tube-   25 treated-matter ejecting unit-   25 a first ejection side valve (second switching means)-   25 b second ejection side valve (second switching means)-   25 c third ejection side valve-   26 first vapor ejection pipe (vapor ejection unit)-   26 a flow rate adjustment valve-   27 pressure gauge-   28 condenser-   29 treatment facility (separation treatment unit)-   31 supply chamber-   31 a leak channel-   31 b leak valve-   32 feeder-   33 first sludge pipe-   34 second sludge pipe-   35 third sludge pipe-   41 rotation axis-   42 stick unit-   43 blade unit-   44 seal structure-   45 elastic buffer-   51 horizontal heat transfer tube-   52 vertical heat transfer tube-   53 second vapor ejection pipe-   54 feedwater supply pipe-   55 flowmeter-   56 feedwater tank-   57 pipe-   61 ejection chamber-   61 a leak channel-   61 b leak valve-   62 treated-matter tank-   63 first treated-matter pipe-   64 second treated-matter pipe-   65 third treated-matter pipe-   71 separated water pipe (second supply unit, first separated water    channel)-   71 a first branch pipe-   71 b second branch pipe-   71 c first flow rate adjustment valve-   71 d second flow rate adjustment valve-   72 blow off pipe-   72 a flow rate adjustment valve-   73 separated water tank-   73 a separated-water-tank heat exchanger (fifth heat exchanger unit)-   76 fourth treated-matter pipe-   77 fifth treated-matter pipe-   78 sixth treated-matter pipe-   81 biomass fuel manufacturing plant-   82 vapor ejection pipe-   91 biomass fuel manufacturing plant-   92 digester-   93 desulfurization device-   94 desiloxane device-   95 gas engine (internal combustion engine)-   96 gas engine exhaust gas pipe-   97 separated water channel (second separated water channel)-   101 biomass fuel manufacturing plant-   102 third vapor ejection pipe-   103 fourth vapor ejection pipe-   104 fifth vapor ejection pipe-   105 tank-   S space

The invention claimed is:
 1. A hydrothermal treatment device performinghydrothermal treatment by heating high-water-content biomass, thehydrothermal treatment device comprising: a treatment container thatstores the high-water-content biomass; a first supply unit that suppliesthe high-water-content biomass to inside of the treatment container suchthat a space is formed in a vertical upper part of the treatmentcontainer; a stirrer unit that is provided within the treatmentcontainer and stirs the high-water-content biomass such that flows in apredetermined direction occur; and at least one heat transfer tube thatis disposed within the treatment container so as to cross thepredetermined direction and heats the high-water-content biomass withheat of vapor flowing within the heat transfer tube.
 2. The hydrothermaltreatment device according to claim 1, wherein the stirrer unit includesa blade unit disposed so as to tilt from a horizontal plane, the bladeunit rotates about an axial direction extending in a vertical up/downdirection, the blade unit has a radial tip disposed so as to be close toan inner periphery surface of the treatment container, and the heattransfer tube extends in a horizontal direction.
 3. The hydrothermaltreatment device according to claim 1, wherein the stirrer unit includesa plurality of blade units that rotate about an axial directionextending in a vertical up/down direction, the plurality of blade unitsare disposed at equal intervals along a circumferential direction of theaxial direction at positions separated by a predetermined distance in aradial direction from the axial direction about which the blade unitsrotate, and each of the blade units is disposed so as to tilt at apredetermined angle toward a direction of the rotation from a horizontalplane, the heat transfer tube extends in a horizontal direction, and theflows in the predetermined direction are counter flows including flowsin the vertical up direction and the vertical down direction.
 4. Thehydrothermal treatment device according to claim 1, further comprising asecond supply unit that supplies water or vapor to the treatmentcontainer such that at least a part of stored matter within thetreatment container keeps a predetermined water content.
 5. Thehydrothermal treatment device according to claim 1, wherein thetreatment container includes an outer shell having a body part forming aside surface and a bottom surface and a ceiling part forming a verticalupper surface, and a fixing unit that fixes at least one of the heattransfer tubes to the body part, the ceiling part is removably fixed tothe body part, and the fixing unit is removably fixed to the body part.6. The hydrothermal treatment device according to claim 1, furthercomprising: a supply chamber that supplies the high-water-contentbiomass to the treatment container; an ejection chamber from whichstored matter stored within the treatment container is ejected; a firstswitching means that switches between a state that the supply chamberand the treatment container are in communication and a state that thesupply chamber and the treatment container are isolated; and a secondswitching means that switches between a state that the ejection chamberand the treatment container are in communication and a state that theejection chamber and the treatment container are isolated, wherein, bykeeping a temperature and a pressure within the treatment container at apredetermined temperature and pressure, the high-water-content biomassis supplied from the supply chamber to the treatment container, and thestored matter is ejected from the treatment container to the ejectionchamber.
 7. The hydrothermal treatment device according to claim 1,further comprising a control unit that adjusts a speed of rotation ofthe stirrer unit during hydrothermal treatment within the treatmentcontainer such that a temperature difference depending on positions ofthe high-water-content biomass within the treatment container is withina predetermined temperature difference range.
 8. A biomass fuelmanufacturing plant including the hydrothermal treatment deviceaccording to claim 1, the biomass fuel manufacturing plant comprising: adewaterer unit that dewaters the high-water-content biomass havingundergone hydrothermal treatment in the hydrothermal treatment device; afirst separated water channel that guides separated water separated fromthe high-water-content biomass in the dewaterer unit to the treatmentcontainer; a vapor ejection unit that ejects vapor occurring within thetreatment container to outside of the treatment container; and aseparation treatment unit that separates impurities from the vaporejected from the vapor ejection unit.
 9. The biomass fuel manufacturingplant according to claim 8, further comprising: a plurality of branchpipes which are branched off from the first separated water channel,wherein the plurality of branch pipes are in communication withdifferent positions in the vertical up/down direction of the treatmentcontainer.
 10. The biomass fuel manufacturing plant according to claim8, further comprising a blow off pipe that externally ejects apredetermined proportion of separated water separated in the dewatererunit.
 11. The biomass fuel manufacturing plant according to claim 8,further comprising: a boiler that generates vapor with heat ofcombustion of a charged fuel and supplies the generated vapor to theheat transfer tube; and a first heat exchanger unit that heat-exchangesbetween the high-water-content biomass having undergone the hydrothermaltreatment in the hydrothermal treatment device and boiler exhaust gasejected from the boiler.
 12. The biomass fuel manufacturing plantaccording to claim 8, further comprising: a digester to which thehigh-water-content biomass before being supplied to the treatmentcontainer is introduced; a second separated water channel that guidesthe separated water separated from the high-water-content biomass in thedewaterer unit to the digester; an internal combustion engine thatdrives by burning fuel gas for the internal combustion engine containingfuel gas ejected from the digester; and a second heat exchanger unitthat heat-exchanges between the high-water-content biomass havingundergone the hydrothermal treatment in the hydrothermal treatmentdevice and internal combustion engine exhaust gas ejected from theinternal combustion engine.
 13. The biomass fuel manufacturing plantaccording to claim 8, further comprising: a boiler that generates vaporwith heat of combustion of a charged fuel and supplies the generatedvapor to the heat transfer tube; a digester to which thehigh-water-content biomass before being supplied to the treatmentcontainer is introduced; a second separated water channel that guidesthe separated water separated from the high-water-content biomass in thedewaterer unit to the digester; an internal combustion engine thatdrives by burning fuel gas for the internal combustion engine containingfuel gas ejected from the digester; and a third heat exchanger unit thatheat-exchanges between the high-water-content biomass having undergonethe hydrothermal treatment in the hydrothermal treatment device andboiler exhaust gas ejected from the boiler and internal combustionengine exhaust gas ejected from the internal combustion engine.
 14. Thebiomass fuel manufacturing plant according to claim 8, furthercomprising a fourth heat exchanger unit that heat-exchanges between thehigh-water-content biomass having undergone the hydrothermal treatmentin the hydrothermal treatment device and vapor ejected from the heattransfer tube.
 15. The biomass fuel manufacturing plant according toclaim 8, further comprising a fifth heat exchanger unit thatheat-exchanges between vapor ejected from the heat transfer tube and theseparated water ejected from the dewaterer unit.
 16. The biomass fuelmanufacturing plant according to claim 8, further comprising: ahigh-water-content biomass tank that stores the high-water-contentbiomass to be supplied to the treatment container; and a sixth heatexchanger unit that heat-exchanges between vapor ejected from the heattransfer tube and the high-water-content biomass within thehigh-water-content biomass tank.
 17. A hydrothermal treatment methodperforming hydrothermal treatment by heating high-water-content biomass,the hydrothermal treatment method comprising: a supplying step ofsupplying the high-water-content biomass to inside of a treatmentcontainer such that a space is formed in a vertical upper part of thetreatment container; a stirring step of, by a stirrer unit providedwithin the treatment container, stirring the high-water-content biomasssuch that flows in a predetermined direction occur; and a heating stepof heating the high-water-content biomass with vapor flowing within atleast one heat transfer tube disposed within the treatment container soas to cross the predetermined direction.
 18. A biomass fuelmanufacturing method using the hydrothermal treatment method accordingto claim 17.